Can't seem to get a DataReader to work in C# / SQL Server

I have this code:

我有这个代码:

string strConnect = "Server=DESKTOP-2Q73COU\SQLEXPRESS;Database=LoginApp;Trusted_Connection=True;";
SqlConnection conn = new SqlConnection(strConnect);
conn.Open();

MessageBox.Show("Connected to SSMS.");

string loadMainInfo = "SELECT * FROM Main_Information WHERE Username = " + Globals.username;

SqlCommand cmd = new SqlCommand(loadMainInfo, conn);

SqlDataReader dr = cmd.ExecuteReader();

if (dr.Read())
{
    lblStanding.Text = (dr["Standing"].ToString());
    lblName.Text = (dr["First Name"].ToString()) + " " + (dr["Last Name"].ToString());
    lblTotalHours.Text = (dr["Total_hours"].ToString());
    lblType.Text = (dr["Degree_type"].ToString());
    lblDegree.Text = (dr["Degree"].ToString());
    lblCurrentHours.Text = (dr["Current_hours"].ToString());
}
string strConnect